Major types of widgets are: Desktop widgets, personal web widgets, public web widgets, mobile web widgets.
A desktop widget is a small program designed to run on your desktop. They provide specific information to the user that can be functional. If a computer runs on windows operating system, you can use widget engine and then choose widgets from a number of widgets and install it on your desktop.
An example of common type of widget for desktop is yahoo widgets. You need to download the widget installer and browse yahoo widgets directory and freely use them on your desktop. Other popular widget engines include Dashboard, Google desktop, Microsoft gadgets and spring widgets.
Personal web widgets: Users post the widgets on their personal home pages like myYahoo, iGoogle. Widget will be visible on users customized page such as users browser start page each time when the user is online. It can be viewed only by the user who installs it.
Public web widgets:
A web widget is a piece of code where a user can embed a widget publicly on social networking sites, blogs, online communities, etc. These can be seen by many people and the user can also install on multiple sites. Widgetbox is a widget directory that enables a user to search for a specific type of widget, customize it for own use and then copy, paste the code on your own web pages. Some web widgets include news headlines, games, eBay trackers, weather report widgets.
The benefit of widget is they constantly provide updated content on your websites and help in search engine optimization of your websites. They are simple and easy to use, just copy the code of widgets and paste it onto your site. Increases traffic on your website.